Alkoxy carboxylates have been used as surfactant additives in a variety of settings, such as in shampoos, laundry detergents, and liquid dish washing compositions. These carboxylic acid compositions have additional potential application as oil additives, such as in marine engines, and in situations where water emulsion formation can occur. They may also have cosmetic applications in combination with Guerbet esters which are highly valued cosmetic esters for their exceptional emolliency properties in skin and body creams. Additionally, alkoxy carboxylates are used in tertiary oil recovery processes. However, all such alkoxy carboxylates have only included one carboxylate group.
Reservoir systems, such as petroleum reservoirs, typically contain fluids such as water and a mixture of hydrocarbons such as oil and gas. To remove (“produce”) the hydrocarbons from the reservoir, different mechanisms can be utilized such as primary, secondary or tertiary recovery processes.
In a primary recovery process, hydrocarbons are displaced from a reservoir through the high natural differential pressure between the reservoir and the bottom hole pressure within a wellbore. The reservoir's energy and natural forces drive the hydrocarbons contained in the reservoir into the production well and up to the surface. Artificial lift systems, such as sucker rod pumps, electrical submersible pumps or gas-lift systems, are often implemented in the primary production stage to reduce the bottom hole pressure within the well. Such systems increase the differential pressure between the reservoir and the wellbore intake; thus, increasing hydrocarbon production. However, even with use of such artificial lift systems only a small fraction of the original-oil-in-place (OOIP) is typically recovered using primary recovery processes as the reservoir pressure, and the differential pressure between the reservoir and the wellbore intake declines over time due to production. For example, typically only about 10-20% of the OOIP can be produced before primary recovery reaches its limit, either when the reservoir pressure is so low that the production rates are not economical or when the proportions of gas or water in the production stream are too high.
In order to increase the production life of the reservoir, secondary or tertiary recovery processes can be used. Secondary recovery processes include water or gas well injection, while tertiary methods are based on injecting additional chemical compounds into the well, such as surfactants and polymers. Typically in these processes, fluids are injected into the reservoir to maintain reservoir pressure and drive the hydrocarbons to producing wells. An additional 10-50% of OOIP can be produced through tertiary recovery processes in addition to the oil produced during primary recovery.
While surfactants can be used as wetting agents, emulsifiers, detergents and solubilizers, they are also utilized in various stages of hydrocarbon recovery and processing, such as in drilling operations (e.g., drilling fluids/dispersants), reservoir injection (e.g., fracturing fluids, enhanced oil recovery fluids), well productivity (e.g., acidizing fluids), hydrocarbon transportation, environmental remediation, or a combination thereof.
Alkylaryl carboxylates have been used as enhanced oil recovery surfactants, such as described in U.S. Pat. No. 6,269,881, incorporated herein in full by reference, with one carboxylate group. There is a need for improved additive compositions for use in EOR applications.